1. Field of the Invention
The present invention relates to computer storage devices, such as disk drives, and, more particularly, to apparatus for loading and unloading the read/write heads of a disk drive onto, and off of, a rotating storage medium, and for protecting the read/writes heads from damage due to shock and, in the case of removable cartridge disk drives, from damage that might result during media insertion.
2. Description of the Prior Art
Disk drives for storing electronic information are found in a wide variety of computer systems, including workstations, personal computers, and laptop and notebook computers. Such disk drives can be stand-alone units that are connected to a computer system by cable, or they can be internal units that occupy a slot, or bay, in the computer system. Laptop and notebook computers have relatively small bays in which to mount internal disk drives and other peripheral devices, as compared to the much larger bays available in most workstation and personal computer housings. The relatively small size of peripheral bays found in laptop and notebook computers, can place significant constraints on the designer of internal disk drives for use in such computers. Techniques that address and overcome the problems associated with these size constraints are therefore important.
Disk drives of the type that accept removable disk cartridges have become increasingly popular. One disk drive product that has been very successful is the ZIP.TM. drive designed and manufactured by lomega Corporation, the assignee of the present invention. ZIP.TM. drives accept removable disk cartridges that contain a flexible magnetic storage medium upon which information can be written and read. The disk-shaped storage medium is mounted on a hub that rotates freely within the cartridge. A spindle motor within the ZIP.TM. drive engages the cartridge hub when the cartridge is inserted into the drive, in order to rotate the storage medium at relatively high speeds. A shutter on the front edge of the cartridge is moved to the side during insertion into the drive, thereby exposing an opening through which the read/write heads of the drive move to access the recording surfaces of the rotating storage medium. The shutter covers the head access opening when the cartridge is outside of the drive, to prevent dust and other contaminants from entering the cartridge and settling on the recording surfaces of the storage medium.
The ZIP.TM. drive is presently available for workstations and personal computers in both stand-alone and internal configurations. In order to provide a version of the ZIP.TM. drive for use in laptop and notebook computers, the size constraints of the peripheral bays of such computers must be considered. In particular, for an internal drive to fit in the majority of laptop and notebook peripheral bays, the drive must be no longer than 135 mm. The height of the drive must be in the range of 12 to 15 mm. These dimensions place many constraints on the design of such a drive, and give rise to numerous design problems. Various aspects and features of the present invention address and overcome several of these problems.
In particular, the ZIP.TM. drive employs a pair of opposing read/write heads for recording and reproducing information on both sides of the storage medium within a ZIP.TM. disk. The opposing read/write heads are disposed on flexible load beams at the distal ends of respective actuator arms, that allow the heads to fly closely over the respective surfaces of the rotating disk. In presently available internal and external versions of the ZIP.TM. drive, loading/unloading ramps are employed to spread the read/write heads apart as the head actuator is moved to a retracted position, in which the heads are moved back away from the edge of the storage medium. This process is described, for example, in commonly assigned, co-pending patent application Ser. No. 08/324,895, filed Oct. 18 , 1994, entitled "Head LoadlTnload and Cleaning in a Data Storage Device" As disclosed therein, wings attached to the load beams of the actuator ride on opposed ramps fixedly disposed in the drive, as the carriage of the linear actuator moves toward and away from the disk. As the heads move toward the disk, the wings ride down the opposed ramps, bringing the heads together onto the disk in a controlled manner. As the linear actuator is withdrawn away from the disk, the wings ride up the opposed ramps to again separate the heads. In this retracted position, disk cartridges can be inserted and removed from the disk drive without harming the read/write heads, since they are retracted backwardly a sufficient distance from the edge of the disk cartridge media. U.S. Pat. No. 4,663,683 (McNeil) discloses another structure in which wings attached to load beam members ride upon ramped surfaces, or cams, to move the read/write heads of a disk drive onto, and off of, a rotating storage medium. In the actuator disclosed in U.S. Pat. No. 4,663,683, as well as in commonly assigned U.S. Pat. No. 5,530,607, the wings are separate components that must be assembled, or attached, to the load beams during disk drive manufacture.
Because a version of the ZIP.TM. drive to be used in laptop and notebook computers is preferably only 135 mm in length, and because the size of the ZIP.TM. cartridge is already established, there will not be enough room in such a drive to be able to retract the heads completely away from the storage medium. As a result, there is a need for a means of protecting the heads during insertion and withdrawal of a disk cartridge. Additionally, vertical size constraints increase the potential for the read/write heads to be damaged when the disk drive undergoes a shock or extreme vibration, as can occur during the handling of a laptop or notebook computer. Various novel and inventive aspects of the present invention address these problems. Also, due to the size constraints and the relative complexity of disk drive devices, there is a need to simplify assembly processes and to reduce the number of parts of disk drives. Other aspects of the present invention satisfy this need.